Semiconductor Arrangement in Power Converters for Overvoltage
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Solution Overview
Problem
In electric power conversion devices for railroad rolling stock, existing arrangements of semiconductor elements in coolers lead to increased parasitic inductance and overvoltage during switching, causing damage and requiring additional snubber circuits that increase size and weight, while also reducing cooling efficiency.
Innovation Solution
The semiconductor elements are arranged in a three-level configuration on the cooler heat receiving part, with elements of higher heat generation positioned for maximum cooling performance and parasitic inductance minimized by shortening circuit paths, eliminating the need for snubber circuits by optimizing terminal orientations and positions for efficient self-cooling or forced cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semiconductor elements are arranged in conventional configurations in the cooler, then the device structure is simple, but parasitic inductance increases and overvoltage occurs during switching
Solution Approach 1:
The patent applies local quality by differentiating the arrangement positions of semiconductor elements based on their specific functions and heat generation characteristics. High heat-generating elements (IGBTs) are positioned at specific locations (e.g., lower positions or positions with better airflow access) while diodes are arranged differently, optimizing both thermal management and electrical performance locally rather than using a uniform arrangement pattern throughout the cooler.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement in the cooler, positioning semiconductor elements at different heights, depths, and horizontal positions. This multi-dimensional placement optimizes circuit path lengths to reduce parasitic inductance while maintaining effective cooling, moving beyond simple two-dimensional planar arrangements to exploit the full volumetric space of the cooler structure.
2Reliability
If snubber circuits are added to suppress overvoltage, then reliability improves, but size and weight of the cooler increase
Solution Approach 1:
The patent converts the potentially harmful effect of circuit inductance into a beneficial arrangement strategy. By carefully designing the circuit paths and element positions, the inherent inductance of the cooler structure is minimized through optimized routing, turning what could be a source of overvoltage problems into an opportunity for natural overvoltage suppression without requiring additional snubber circuits.
Solution Approach 2:
The cooler structure itself is designed to provide overvoltage suppression functionality through its internal circuit path optimization, eliminating the need for separate protective components. The arrangement of semiconductor elements and their connection paths within the cooler creates inherently lower parasitic inductance, allowing the system to protect itself against overvoltage without external assistance from snubber circuits.
3Temperature
If cooling performance is maximized by optimizing element positions, then temperature control improves, but parasitic inductance increases
Solution Approach 1:
The patent employs asymmetric arrangement of semiconductor elements within the cooler, positioning IGBTs and diodes at non-uniform locations that are optimized for both thermal and electrical performance. The asymmetric layout allows circuit paths to be routed more efficiently, reducing loop areas and parasitic inductance while maintaining optimal thermal contact with cooling channels, breaking the symmetry that would otherwise force compromise between thermal and electrical optimization.
Solution Approach 2:
The patent performs preliminary optimization of the semiconductor element arrangement during the design phase, pre-configuring the positions to simultaneously minimize both thermal resistance and parasitic inductance. By establishing the optimal layout before manufacturing, the design anticipates and prevents the trade-off between cooling efficiency and electrical performance, rather than requiring post-manufacturing adjustments or compromising designs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This arrangement enhances cooling performance, reduces the size and weight of the cooler, and suppresses overvoltage without adding snubber circuits, thereby improving the reliability and efficiency of the electric power conversion device.
Implementation Method 1
a cooler used in an electric power conversion device is basically composed of a heat receiving part on which semiconductor elements are mounted and a heat radiating part which radiates heat to the ambient air
Implementation Method 2
the heat radiating part is placed in an open chamber portion in communication with the ambient air
Data Source
AI summary
Semiconductor element groups constituting a unit are mounted on a cooler heat receiving part 1 on the same plane and are adapted to radiate heat by self-cooling or cooling by wind. First and fourth semiconductor elements Q1, Q4 are arranged on the lower side of the cooler heat receiving part, second and third semiconductor elements Q2, Q3 are arranged in the middle, a first diode D5 and a second diode D6 are arranged on the upper side, the first and second semiconductor elements Q1, Q2, as well as the third and fourth semiconductor elements Q3, Q4 are each arranged in positions opposite to each other in a horizontal direction with respect to a centerline of a cooler in a vertical direction.